Currently:

 

Made 1 land border run, if I make another that should be the max I'm allowed using visa exemption.. my question is if I where to do this(get a second one).. :

 

would I (a) be able to leave get a setv at Vientiane and get back in after the second land border run, runs out ?

 

And (b) would I be able still arrive in BKK in transit exiting the region if I can't get another visa ?

If you did your previous visa exempt entry at a land border crossing was done last year the count was reset at the start of this year which means you can get 2 this year.

There is no restriction on doing visa exempt entries by air.

Vientiane does not count the number of visa exempt entries you have when you apply for a visa.

If you have a visa for entry it is not affected by the number of visa exempt entries you have done at land border crossings.

 

I currently hold H1B visa for Thailand and I wish to know if exempts me from visiting neighbouring countries as a tourist. It is single entry. Anything like schengen visa operates in the region, please inform me, thanks

2 minutes ago, Master Jairam said:

I currently hold H1B visa for Thailand and I wish to know if exempts me from visiting neighbouring countries as a tourist. It is single entry.

Thailand does not have visa called that. Perhaps you have a single entry non-b visa. It only allows one 90 day entry to the country.

1 minute ago, ubonjoe said:

Thailand does not have visa called that. Perhaps you have a single entry non-b visa. It only allows one 90 day entry to the country.

Under another topic just now I asked about if I wanted to go home, here may I ask if I want to visit say Cambodia what I should do. Yes you are right, I have a non-imm b visa. 

11 minutes ago, Master Jairam said:

Under another topic just now I asked about if I wanted to go home, here may I ask if I want to visit say Cambodia what I should do. Yes you are right, I have a non-imm b visa. 

If you want to travel during the 90 days you can get a re-entry permit that will keep the remainder of the 90 days valid when you enter the country.